Abstract: A serious experiment of CO2 laser-tungsten inert gas(TIG) arc hybrid welding was used to weld the 316L stainless steel with Rofin Sinar 5kW CO2 laser and Miller TIG welding machine.The effect of various parameters such as laser power,arc current and the laser-arc distance on the welding shape was studied in detail.The result showed that there was a "key hole" when the laser power was above 2.5kW,which dominantly affected the weld penetration;the weld width was relative to the power of the laser and energy of the arc when the arc current was less than 150A,but the weld width was determined by the energy of the arc only when the arc current was larger than 150A.There was an optimal laser-arc distance(2mm~3mm),with which the weld penetration can be improved to 1.46 times~2.54 times.The research shows that the hybrid welding can improve the weld ability of 316L stainless steel.